Using CAAnimationGroup for View Animations

Lately I have been pushing myself to increase my knowledge and understanding of more advanced animation techniques. The more that I
dig into the lower level core graphics framework and core animation the more impressed I become with their power. I also have a greater 
respect for those developers who can leverage their power in creative ways.

For most use cases leveraging uiview basic animations with blocks will do exactly what you need. However, in my particular case I wanted to
accomplish the following. Scale, rotate and change center point of subview "A" to subview "B" all at the same time.

Taking my own advise I first started down the path of using basic uiview animations. I want to make sure that each different piece of
the animation would perform the way I wanted them to. Separately, they did exactly what I wanted. Unfortunately, grouping these together was
not going to happen with uiview animations.

When I ran the process all the animations executed, but the transition to subview b's center point was very jerky. To make sure that I didn't
miscalculate any of the individual animations I went back and tested each one separately. Each animation ran smoothly. When I ran the group within the block
I had the jerkiness problem of animation the center point.

After going back and reviewing Apple documentation I found what my problem was. Imagine that. To do the rotation I apply a transform on
the view's layer. However, the transform performs it's animation based upon the views center point. Since I was trying to apply an
animation on the center point as well the group animation had to reposition subview A's center point first before it could apply any of
the other animations. Hence the jerkiness.

I pushed all my animations to a CAAnimationGroup and all the transitions were performed.


-- 
Cory D. Wiles
kwylez@gmail.com
www.corywiles.com | twitter.com/kwylez

Creating Custom Glossy Gradient Buttons Programmatically

As my experience, and hopefully skill, in iPhone development has matured over the past year and half I am in the constant search for the best techniques for my apps to run better, faster, and consequently more efficient.  Of the top developers that I follow they all make references to the importance of utilizing subclasses of UIViews and the underlying subsets of views in general.

I love the UI elements that are used on the phone. I didn't realize the awesome power of CoreAnimation and the flexibility that it gives you to manipulate and create graphics as such a granular level.  I set out to see if I could recreate a common iPhone UI element completely programmatically: a glossy gradient button that still responds to touch events.

The end result was a success and a great learning experience.  I still need to add in more testing to make sure that interacting with all these views is more efficient than interacting with standard pngs.

This biggest issue that I ran into was "re-enable" the button actions.

Simply subclassing UIButton did create a problem when dealing with the UIControlEventTouchUpInside/UIControlEventTouchUpOutside methods that you associate with buttons.

I was able to overcome this issue by implementing the touchesBegan and touchesEnded methods.  Remember...UIButton inherits from UIControl, which in-turn inherits from UIView.

Problem solved.

Download Project

UIViews with Rounded Corners and Animations

One of the best iPhone reference books on the market today is iPhone SDK Development by Bill Dudney and Chris Adamson, published by Pragmatic Programmers.  The examples are real-world, easy to follow and cover just about any area of development that one needs.  In my earlier projects and example code I tended to use a lot of graphics for buttons and backgrounds because I need something with rounded corners and/or a gradient.  However, in my latest project I have wanted to get away from that and utilize CoreAnimation and more UIView drawing techniques and the results have been outstanding.  Load time on my views are much faster because all the drawing and rendering are done on the compiled view level and not from the rendering of an image.

 I created a sample project that loads a three different views onto the controller and animates them.  There is nothing overly complex about the code at all and can be customized to be more configurable, but is written to show the power and flexibility of creating custom views and animations.

::NOTE::
The rounded corner drawing in the project was sample code from the iPhone SDK Development Book.  Credit where  credit is due to Bill and Chris.

As always I encourage anyone who downloads the project to make any modifications and/or enhancements.  For example, you could add in the functionality of firing of the animation based upon text field values or randomizing the speed of the animation.

SlideView Contribution

One of my favorite iPhone related sites to read is iPhone Developer Tips.  The tutorials are outstanding and most importantly "real world" useful.  Back in August there was a blog posted showing how to implement a "slideable" message that can be presented to a user.  After reading through it I decided to modify how it was used to make it a little more extensible for an iPhone project that I am working.  After I got everything working correctly and they way I wanted to I decided to contact the site owner, John, with all of my source code in case he wanted to use it.

After a little more tweaking to my code he posted my changes, as well as another developer, Greg's code in a new post.

This is a small example of the importance of using open source software, as well as, the importance for developers to use the knowledge and skills of other developers to make the good....GREAT.

Sliding Views On and Off Screen – Part 2 – Reader Contributions